The present invention relates to a new and improved method of manufacturing a multi-phase thermal circuit breaker, and to a new and improved multi-phase thermal circuit breaker manufactured thereby.
In its more particular aspects, the method of manufacturing the multi-phase thermal circuit breaker comprises the steps of mounting each of a multiple number of bimetallic elements, each of which contains a bendable section which acts upon a common actuator member, at a support and mounting the supports in juxtaposition to each other at a retainer or holder member.
As to the circuit breaker of the present development such is of the type comprising a multiple number of bimetallic elements, each associated with one phase, and each bimetallic element comprises a bendable section or portion arranged to act upon a common actuator member. Each of the bimetallic elements is mounted at a support which, in turn, is secured to a retainer or holder member.
In multi-phase bimetallic circuit breakers of such type the bimetallic elements each associated with one respective phase act upon a common actuator member which, as a general rule, is designed as a slider. It must be ensured by appropriate measures that all bimetallic elements exert the same effect upon the actuator member when they are heated-up in the same manner. That is to say, the bending sections or portions of all the bimetallic elements must assume the same position relative to the actuator member at a defined ambient temperature and in the absence of current flow through the bimetallic elements.
In a prior art circuit breaker known, for example, from Swiss Pat. No. 558,593 there is measured for this purpose the mutual distances between the freely bendable end portions of the bimetallic elements after the bimetallic elements have been mounted in the housing. On the basis of the thus determined distances an individual slider is manufactured for this particular circuit breaker. Since, in addition to measuring the mentioned distances an individual slider or slide member has to be manufactured for each circuit breaker, this solution is rather expensive in respect of the work involved, something which is disadvantageous in terms of the manufacturing costs even in the case of automated production.
Furthermore, a bimetallic circuit breaker as known, for example, from Swiss Pat. No. 216,532, has bimetallic elements, each of which is secured to a support at one of its ends, and the support is pivotably mounted at a housing. Prior to the installation of the circuit breaker there is adjusted the position of each individual bimetallic element relative to the actuator member, which is designed as a controlling slider, by pivoting the individual supports in such a way that at a defined ambient temperature the distance between the bendable free ends of the bimetallic elements and abutting edges formed at the controlling slider is the same for all the bimetallic elements. This adjustment, which additionally requires some dexterity on the part of the installator, however, is very time-consuming and expensive and is unsuited for an automated manufacturing mode.
A further construction of circuit breaker is known from Swiss Pat. No. 400,319.